Chapter17 (1) 2

Chapter 17: Assessment of Respiratory Function

Wolters Kluwer

Overview of the Respiratory System

• Tracts:

  • Upper Respiratory Tract: Warms and filters air.

  • Lower Respiratory Tract (Lungs): Accomplishes gas exchange.

• Function:

  • Delivers oxygen and expels carbon dioxide from the body.

  • Works with the circulatory system to maintain homeostasis.

Structures of the Upper Respiratory Tract

Components:

• Nose:

  • Passageway for air to and from the lungs.

• Paranasal Sinuses:

  • Frontal, Ethmoid, Sphenoid, Maxillary

• Pharynx:

  • Includes Nasal, Oral, and Laryngeal areas.

Structures of the Lower Respiratory Tract

Components:

• Two Lungs:

  • Left Lung: Upper and Lower lobes.

  • Right Lung: Upper, Middle, and Lower lobes.

• Other Structures:

  • Pleura, Mediastinum, Bronchi, Bronchioles, Alveoli.

Alveoli

• Function:

  • Site for gas exchange (diffusion of oxygen and carbon dioxide).

• Key Components:

  • Alveolar-capillary membrane, types of alveolar cells, surfactant.

Functions of the Respiratory System

Key Functions:

• Oxygen Transport:

• Respiration and Ventilation:

  • Factors: air pressure variances, airway resistance, compliance, lung volumes, and capacities.

• Pulmonary Diffusion and Perfusion:

• Ventilation-Perfusion (V/Q) Balance:

  • Imbalance can lead to hypoxia.

Gas Exchanges and Respiratory Function

Important Concepts:

• Partial Pressure of Gases:

• Oxyhemoglobin Dissociation Curve:

• Carbon Dioxide Transport:

• Neurologic Control of Ventilation:

Perfusion

Oxygen Transport:

• Oxygen crosses alveolar-capillary membrane into arterial blood by diffusion, aided by perfusion.

Carbon Dioxide Transport:

• CO2 is produced by metabolic combustion and diffuses from tissues into the blood returning to the lungs.

Respiration

• Definition:

  • Process of gas exchange between atmospheric air and blood, as well as blood and body cells.

• Oxygen flows from alveoli to blood due to concentration gradient.

Ventilation

Mechanics of Breathing:

• Inspiration:

  • Diaphragm contraction and external intercostal muscle contraction enlarge thoracic cavity, creating negative pressure to draw air in.

• Expiration:

  • Diaphragm relaxation creates positive pressure, pushing air out.

Lung Capacity

Lung Volumes:

• Tidal Volume (TV):

  • ~500 mL, air inspired during relaxed breathing.

• Inspiratory Reserve Volume (IRV):

  • ~3,100 mL, additional air inhaled after normal tidal volume.

• Expiratory Reserve Volume (ERV):

  • ~1,200 mL, additional air exhaled after normal tidal volume.

• Vital Capacity (VC):

  • VC = TV + IRV + ERV.

Diagnostic Evaluation

Methods:

• Pulmonary Function Tests:

• Arterial Blood Gases:

• Pulse Oximetry: Non-invasive oxygen saturation monitoring.

• End-tidal Carbon Dioxide Monitoring:

• Imaging Studies: Helps in visualizing respiratory structures.

Sample Collection for Sputum

• Best Time to Collect:

  • Early morning after the patient clears the nose and throat.

• Purpose:

  • Diagnose infections and assess for malignant cells.

Comprehensive Respiratory Assessment

Components:

• Health History and Presenting Problems:

  • Onset, Location, Duration, Symptoms Impacting Daily Activities.

• Physical Assessment:

  • General appearance indicators, upper airway inspection, auscultation techniques (Tables for specific sounds).

Respiratory Control by the Brain

Receptors Involved:

• Chemoreceptors, Mechanoreceptors, Proprioceptors:

  • Work together to regulate respiratory rates based on body needs.